JPH08124119A - Thin-film magnetic head assembly - Google Patents

Abstract

PURPOSE: To impart stable floating to a slider while assuring the degree of freedom of the slider by connecting bonding pads to each other to an optimum positional relation by means of wires. CONSTITUTION: This thin-film magnetic head assembly is composed of the slider 2, a flexible wiring board 4, gimbals 3 and the wires 13. The slider 2 has a thin-film magnetic head element 1 and the bonding pads 5 on its side face and is worked with rails in such a manner that its rear surface acts as a floating surface. The front surface of the slider is joined to the prescribed position of the joint part 30 of the gimbals 3 having a spring characteristic. The flexible wiring board 4 is stuck onto the gimbals 3 and has wiring conductors 41 and the bonding pads 40. The flexible wiring board 41 is adhered to the prescribed position on the gimbals 3 in such a manner that the positional relation between the surfaces of the bonding pads 40 of the wiring board 4 and the surfaces of the bonding pads 5 of the slider 2 is made nearly perpendicular. The bonding pads 40, 5 are connected to each other by the wires 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head assembly used in magnetic disk devices, magnetic tape devices and the like.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing the structure of a thin film magnetic head assembly that has been put into practical use. This will be described using 5. The thin film magnetic head assembly 10 includes a slider 2 having a thin film magnetic head element 1 on its side surface, a gimbal 3 for holding the slider, and a wire for electrically connecting the bonding pad 5 of the magnetic head element to the outside. It is composed of 13. Since the wire may come into contact with a gimbal or the like, an Au-plated Cu wire coated with insulation is usually used. However, in this case, it is difficult to automate because there are processes such as wiring of wires, and the assembly is performed manually, and an electrical connection method of the thin film magnetic head assembly suitable for automation is also desired to shorten the process. ing.

Further, when the connection is made by the above structure, the load caused by the wire adversely affects the flying posture of the slider due to the high rigidity of the Au-plated Cu wire. Therefore, a redundant portion called a service loop (A portion in FIG. 5) is provided on the wire to reduce the influence. However, when the flying height exceeds 0.1 μm in the above structure, it did not become a problem, but in recent years when the recording density has increased, the slider has become smaller and the flying height has fallen below 0.1 μm. The use of service loops has become insufficient to mitigate the effects of wire load. Further, since the service loop has a structure that greatly extends to the side surface of the slider, it often comes into contact with an operator's hand, a jig, or the like in the manufacturing process of the magnetic disk device and causes deformation, which adversely affects the operation.

Several structures have been proposed as a method of electrically connecting a thin-film magnetic head assembly that solves the problems of the prior art.

In Japanese Utility Model Laid-Open No. 61-153117, an electrical connection is made in which a signal extraction bonding pad on a flexible wiring board arranged at a bent portion of a gimbal and a bonding pad of a thin film head are connected by a wire. A method has been proposed. In this configuration, since the magnetic head and the bonding pads of the flexible wiring board are arranged on the parallel surfaces, it is easily imagined that they can be connected by a normal wire bonding apparatus. However, this structure is limited to the case where the bonding pad of the magnetic head is attached to the surface orthogonal to the longitudinal direction of the gimbal, and the structure used in a small magnetic disk device in recent years, that is, the bonding pad of the magnetic head is the longitudinal direction of the gimbal. It cannot be applied to a so-called in-line type thin film magnetic head assembly located on the direction line.

Further, Japanese Patent Laid-Open No. 61-160815 proposes a method of bending a flexible wiring board, disposing the flexible wiring board close to the thin film head element on the side surface of the slider, and performing electrical connection by bonding. Although the wiring material of the flexible wiring board is not described here, Cu is generally common, and the cross-sectional area cannot be reduced in consideration of resistance, so that the rigidity of this wiring is considerably large. Especially 4 like the inductive-MR composite head
It can be easily imagined that the problem will be more serious when more than two wirings are required.

Further, in the above two configurations, the wire bonding method is not specifically described. The slider must be fixed in order to perform bonding to the bonding pad in the head element, but it is very difficult to fix the slider when the slider is small and the head and gimbal are assembled.

A wire bonding apparatus for connecting two pad portions on two vertical surfaces is disclosed in Japanese Patent Laid-Open No. 1965/1992.
No. 49. However, even in this case, the method of holding the work is not described in detail, and it is difficult to directly apply this configuration to the connection of the magnetic head.

[0009]

In a thin-film magnetic head assembly mounted on a magnetic disk device, the miniaturization of the device complicates the handling of the electrical connection method particularly during mass production, and automation is strongly desired. . At that time, it is necessary to secure the rigidity and reliability of the wire.
As described above, since the thin film magnetic head assembly which is widely used at present is not suitable for automation and uses Cu wire having high rigidity, there is a problem that the flying posture of the head slider is adversely affected. is there.

The present invention has been made in view of the above circumstances, and provides a thin film magnetic head assembly provided with an electrical connection method which is excellent in mass productivity and reliability and which can provide a stable flying posture.

[0011]

A thin-film magnetic head assembly according to the present invention detects a thin-film magnetic head element and a signal from the thin-film magnetic head element on the same plane which is perpendicular to a slider's air bearing surface facing a magnetic medium. And a bonding pad for adhering the slider, a gimbal having a bonding portion at a predetermined position for bonding the slider, a flexible wiring board having a bonding pad at an end of a wiring conductor, and a wire. The upper surface of the slider is adhered to the joint portion of the gimbal, and the flexible wiring board has a bonding pad of the flexible wiring board and a bonding pad of the slider that are substantially perpendicular to each other. Is bonded to the gimbal at a predetermined position, and the space between the bonding pads is fixed by the wire. Constituted by a thin film magnetic head assembly, characterized in that it is continued.

[0012]

According to the present invention, the bonding pads of the flexible wiring board and the bonding pads of the slider 1 are arranged such that the positional relationship between them is substantially right, and the bonding pads are connected by wires in an optimal positional relationship. Therefore, it is possible to electrically connect a thin film magnetic head with excellent mass productivity and reliability, and by selecting the wire diameter and material, the degree of freedom of the slider can be secured and stable flying can be provided. it can.

[0013]

【Example】

(Embodiment 1) FIG. 1 is a perspective view showing an embodiment of the present invention. The thin film magnetic head assembly includes a slider 2, a flexible wiring board 4 (hereinafter referred to as FPC), a gimbal 3,
It is composed of a wire 13. The slider has a thin film magnetic head element 1 and a bonding pad 5 on its side surface, and its lower surface is rail processed so that it operates as an air bearing surface. Further, the upper surface of the slider is bonded to the joint portion 30 of the gimbal 3 having a spring property at a predetermined position. Also FPC
Is attached to the gimbal and has a wiring conductor 41 and a bonding pad 40.

In the present invention, the bonding pad of the above-mentioned element and the bonding pad on the FPC are on a plane perpendicular to each other, and each surface is plated with Au. The two bonding pads were connected by wire bonding using Au wire, specifically ball bonding. The first side is the thin-film magnetic head element, and the second side is the FPC.

In ball bonding, it is general to apply heat and ultrasonic waves at the same time, and heating at about 150 ° C. is performed at the time of bonding on an IC chip or the like. However, in this embodiment, an adhesive is used to connect the slider and the gimbal and the gimbal and the FPC, and since the softening point of the adhesive is as low as about 80 ° C., the bonding was performed at a low temperature of 50 ° C. Therefore, in order to compensate the bonding force, an appropriate ultrasonic wave application condition was selected. Adequate bonding is performed, and the adhesive strength measurement in the tensile test after bonding is about 5 when using a 25 μm wire.
gf is obtained, which is at a level where there is no problem in use. When a heat-resistant material is used for the adhesive, it is desirable to use ordinary heat and ultrasonic waves in combination for bonding.

(Embodiment 2) Next, a bonding method will be described in detail. The jig used for bonding is an overall perspective view. 2 and an enlarged view of the vacuum chuck portion. 3 will be used for the explanation. Fig. 2, the thin film magnetic head assembly 10 has a moving stage 20.
Drop it into the top two pins 21. And Figure. 3, the slider 2 is pressed against the slider fixing member 25 by the two side surfaces, and the remaining two side surfaces are fixed by another fixing member 28 having a spring property. Further Fig. In 2, the central portion of the gimbal is pressed by an appropriate load by the gimbal pressing member 23 connected to the spring. In this state, move the stage moving lever 22 from A to B direction 90
Rotate once. Along with this, the movable stage connected to the lever rotates 90 degrees, and the surface of the bonding pad of the thin film magnetic head element faces the upper surface. Positioning is performed in this state, and the state in which fast bonding can be performed is obtained.

However, it has been found that the tip of the capillaries presses the slider element surface with a considerable force at the time of the first bonding, so that if the rigidity of the gimbal is weak, the bonding cannot be performed. Therefore, Fig.
As shown in 3, when the slider is just fixed at a predetermined position, a hole 27 smaller than the slider is provided on the fixing surface of the jig that is in contact with the slider floating surface 12, and the vacuum line is connected here to fix the slider by suction. The bonding is now possible. Fig. 3, a hole 26 for a vacuum chuck that is connected to a hole on the fixing surface of the jig that contacts the slider air bearing surface and FIG. 2 is connected to the vacuum chuck line 24,
A three-way cock is connected to this tip (not shown), and suction and leak can be selected by switching. It was confirmed that the slider air bearing surface was rail-processed and had irregularities, but it was sufficient for adsorption and fixation.

The conditions for the first bonding are as follows: bonding load 50 gf, ultrasonic output 0.5 W,
The ultrasonic wave was applied for 60 msec. In FIG.
After the stage moving lever 22 is set to the B position and the first bonding is completed on the bonding pad of the thin film head element, the lever is rotated 90 degrees to return to the A position.
Second bonding is performed on the bonding pad of the FPC attached on the gimbal to complete the wire connection. Second bonding condition is bonding load 9
0gf, ultrasonic output 0.6W, ultrasonic application time 70ms
It went in ec. Since the gimbal flexes slightly during the second bonding, if the slider is completely fixed, the strain may concentrate on the wire and the first bonding part may come off. It is better not to do it. In both first bonding and second bonding, ultrasonic output is 0.3W or less, ultrasonic application time is 40
If it is less than msec, sufficient bonding strength cannot be obtained,
On the contrary, ultrasonic output 0.8W or more, ultrasonic application time 80ms
Even under the condition of ec or more, problems such as insufficient bonding strength being obtained and damage to the tip of the capillary occurred.

In the above embodiment, the Au wire is 25 μm.
Use a diameter of m and recommend a wire diameter of 25μ for the capillary.
A bottleneck-type ceramic capillary corresponding to m was used.

Further, it was confirmed that the center of rotation of the rotating system of the moving stage was aligned with the edge of the slider, and the wire loop shape changed depending on this position.

In the present embodiment, the manual operation bonding using the lever is described, but the driving of the moving stage, the vacuum chuck and the like can be performed automatically by using the solenoid valve. It is also possible to automate the bonding by mounting an automatic recognition device.

(Embodiment 3) Since the Au wire is used in the structure of the present invention, the wire and the gimbal should not be in contact with each other.
Further, there is a demand for a thinner magnetic head to be mounted on a drive, and in order to avoid interference between the upper and lower heads, it is necessary to pull the wires apart without contacting them and without separating them from the gimbal surface.

The wire loop shape is selected according to the wire type.
It can be controlled by the bonding conditions. The shape of the bent part is A
This occurs because when Au balls are formed on the u-wire, the Au crystal grains are recrystallized by heat to cause crystal growth and become partially hard. Therefore, the loop shape of the wire can be determined by selecting the wire line type, the bonding condition, and the rotation center of the moving stage rotation system according to the dimensions of the head gimbal assembly designed.

It was confirmed that the height of each of the four Au wires in this example was suppressed to 150 μm or less from the gimbal surface. By suppressing the height of the thin film head assembly as a whole, the thin film head assembly can be easily mounted on a magnetic disk device (HDD), and it is effective in achieving a thinner HDD.

(Embodiment 4) Even in the connecting method of this construction, the rigidity of the wire may exert a load on the slider, which may adversely affect the flying posture and the like. Therefore, the rigidity given by the wires in the pitch direction and the roll direction in the case of four terminals was calculated using the finite element method. This result is shown in Fig. 4 shows.
In the simulation with this head gimbal assembly, it is understood that the wire diameter of Au used for the connection must be 25 μm or less in order to suppress the rigidity below the standard value. This value naturally changes depending on the dimension and the like, but since the slider size will become smaller in the future, the gimbal will be thinner, and the spring property will also be reduced, it is not necessary to set the wire diameter to 25 μm or less in this configuration. It's clear. In the same figure, the measured values of the rigidity of the thin film head assembly in which four wires having a wire diameter of 25 μm are connected are plotted. It can be seen that both the pitch and roll directions agree with the calculated values.

In the above-mentioned embodiments, the ball bonding using Au wire is described. However, it is also possible to use a wire using another material having low rigidity, for example, an alloy containing Al or Au as a main raw material. Needless to say, a thin film head assembly having the same effect can be obtained even if the connection method is wedge bonding, thermocompression bonding, or a method using a laser.

[0027]

As described above, according to the structure of the present invention, since the rigidity given by the wire can be reduced, the flying posture is not adversely affected, and the automation is facilitated, and the thin film excellent in productivity and reliability is obtained. A magnetic head assembly can be provided.

Further, since the thin film magnetic head assembly of the present invention has no wire service loop, it is advantageous for downsizing and is also advantageous for handling during assembly in the manufacturing process of the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a thin film magnetic head assembly of the present invention.

FIG. 2 is a perspective view of a jig used for wire bonding of the present invention.

FIG. 3 is an enlarged sectional view of a slider suction portion of a jig used for wire bonding of the present invention.

FIG. 4 is a diagram showing the relationship between the Au wire wire diameter and the rigidity in the pitch direction and the roll direction in the case of Example 4 of the present invention.

FIG. 5 is a perspective view of a conventional thin film magnetic head assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 thin film magnetic head element 2 slider 3 gimbal 4 flexible wiring board 5 bonding pad 10 thin film magnetic head assembly 11 thin film magnetic head element 12 slider air bearing surface 13 wire 20 moving stage 21 positioning pin 22 stage moving lever 23 gimbal pressing member 24 vacuum Chuck line 25 Slider fixing member 30 Bonding part 40 Bonding pad 41 Wiring conductor

Claims (3)

[Claims] 1. A slider having a thin film magnetic head element and a bonding pad for detecting a signal from the thin film magnetic head element adjacent to each other on a surface of the slider facing the magnetic medium, the surface being perpendicular to the air bearing surface. A gimbal having a bonding portion for adhering the slider one at a predetermined position, a flexible wiring board having a bonding pad at an end portion of a wiring conductor, and a wire. The upper surface is adhered, and the flexible wiring board is adhered to a predetermined position on the gimbal so that the bonding pad surface of the flexible wiring board and the bonding pad surface of the slider 1 form a substantially right angle. The thin film magnetic head assembly is characterized in that the bonding pads are connected by the wires. Li. 2. The thin-film magnetic head assembly according to claim 1, wherein the wire has a diameter of 25 μm or less. 3. The thin film magnetic head assembly according to claim 1, wherein the material of the wire is Au.